Bump actions/checkout from 3 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/code.yml

@@ -18,7 +18,7 @@ jobs:
 
  steps:
  - name: Checkout
- uses: actions/checkout@v3
+ uses: actions/checkout@v4
 
  - name: Install python packages
  uses: ./.github/actions/install_requirements
@@ -51,7 +51,7 @@ jobs:
 
  steps:
  - name: Checkout
- uses: actions/checkout@v3
+ uses: actions/checkout@v4
  with:
  # Need this to get version number from last tag
  fetch-depth: 0
@@ -81,7 +81,7 @@ jobs:
 
  steps:
  - name: Checkout
- uses: actions/checkout@v3
+ uses: actions/checkout@v4
  with:
  # Need this to get version number from last tag
  fetch-depth: 0
@@ -121,7 +121,7 @@ jobs:
 
  steps:
  - name: Checkout
- uses: actions/checkout@v3
+ uses: actions/checkout@v4
 
  # image names must be all lower case
  - name: Generate image repo name

.github/workflows/docs.yml

@@ -15,7 +15,7 @@ jobs:
  run: sleep 60
 
  - name: Checkout
- uses: actions/checkout@v3
+ uses: actions/checkout@v4
  with:
  # Need this to get version number from last tag
  fetch-depth: 0

.github/workflows/docs_clean.yml

@@ -18,7 +18,7 @@ jobs:
 
  steps:
  - name: Checkout
- uses: actions/checkout@v3
+ uses: actions/checkout@v4
  with:
  ref: gh-pages
 

.github/workflows/linkcheck.yml

@@ -17,7 +17,7 @@ jobs:
 
  steps:
  - name: Checkout
- uses: actions/checkout@v3
+ uses: actions/checkout@v4
 
  - name: Install python packages
  uses: ./.github/actions/install_requirements